Download or read book Studies in Counterflow Laminar Flame Theory written by Jong Soo Kim and published by . This book was released on 1991 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experiments in Laminar and Turbulent Premixed Counter flow Flames at Variable Lewis Number written by Sean Salusbury and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis examines preferential diffusion effects in laminar and turbulent premixed combustion. Stretched, fuel-lean, laminar flames of methane, propane and hydrogen are studied experimentally in a counter-flow flame configuration to investigate the effect of Lewis number on stretched flames. Laminar flame results show that a maximum reference flame speed exists for mixtures with Le >= 1 at lower flame-stretch values than the extinction stretch rate. A continually-increasing reference flame speed is measured for Le “ 1 mixtures until extinction occurs when the flame is constrained by the stagnation point.Turbulent counter-flow flame experiments are then performed for these mixtures, using high-blockage turbulence-generating plates to produce turbulence intensities on the order of u'/sLo = 1 to 10. Measurements of average and instantaneous velocity within the turbulent flame are performed by time-resolved particle image velocimetry measurements. Average and instantaneous flame front position is also measured by Rayleigh spectroscopy.Measurements of average turbulent burning velocity demonstrate the ambiguity in definitions of the burning velocity and the difficulty of examining turbulent flame chemistry using averaged measurements. Instantaneous statistics are shown to be superior tools for studying turbulent combustion. The probability-density functions (PDF) of the local flamelet burning velocities for Le >= 1 mixtures show that the instantaneous flamelet burning velocities increase with increasing turbulence intensity and flame stretch. The PDF for the Le ~= 1 mixture has a sharply skewed shape at high turbulence intensity and has a sharp drop-off in probability at a velocity that corresponds with the experimentally-measured maximum reference flame speed from the laminar flame experiments. In contrast, in the Le “ 1 turbulent flames, the most-probable instantaneous flamelet burning velocities increase with increasing turbulence intensity and can significantly exceed the maximum reference flame speed measured in counter-flow laminar flames at extinction.These results are reinforced by instantaneous flame position measurements. Flame front location PDFs show the most probable flame location to be linked to velocity PDFs. Furthermore, hydrogen PDFs are recognizably skewed as u'/sLo increases, indicating a tendency for the Le “ 1 mixture to propagate farther into the unburned reactants. These results support the leading edge theory of premixed turbulent flame propagation for flames in which preferential diffusion effects are expected.In the study of turbulent flames, this work promotes the use of local, instantaneous statistics as a tool for describing experimental results and studying fuel chemistry." --
Download or read book Experimental and Numerical Studies of Laminar Counter flow Diffusion Flames Using Biomass based Gaseous Fuels written by Marie-Theres Scharl and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
Download or read book Theories of Turbulent Combustion in High Speed Flows written by Paul A. Libby and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies on Counterflow Diffusion Flames written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Methods in Laminar Flame Propagation written by Norbert Peters and published by Springer-Verlag. This book was released on 2013-11-21 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Laminar Flames written by J. D. Buckmaster and published by Cambridge University Press. This book was released on 2008-12-04 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph deals with the structure, generation and stability of flames from a mathematical point of view. It uses a specific mathematical approach to provide a unified theoretical description of fundamental flame phenomena. Its importance stems from the fact that it provides the first clear evidence that combustion can be legitimately treated as a mathematical science as well as an empirical one. The book will be of interest to researchers in combustion, fluid mechanics and applied mathematics, as well as to graduate students taking advanced courses in these areas.
Download or read book Propagation and Extinction Studies of Laminar Lean Premixed Syngas Air Flames written by Yang Zhang and published by Springer. This book was released on 2017-07-18 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents pioneering experimental and numerical studies on three aspects of the combustion characteristics of lean premixed syngas/air flames, namely the laminar flame speed, extinction limit and flammability limit. It illustrates a new extinction exponent concept, which enriches the combustion theory. Above all, the book provides the following: a) a series of carefully measured data and theoretical analyses to reveal the intrinsic mechanisms of the fuel composition effect on the propagation and extinction of lean syngas/air flames; b) a mixing model and correlation to predict the laminar flame speed of multi-component syngas fuels, intended for engineering computations; c) a new “extinction exponent” concept to describe the critical effects of chemical kinetics on the extinction of lean premixed syngas/air flames; and d) the effects and mechanism of the dilution of incombustible components on lean premixed syngas/air flames and the preferential importance among the thermal, chemical and diffusion effects.
Download or read book The Extinction and Structure of Counterflow Premixed Flames written by Jesse Keith Crump and published by . This book was released on 1989 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Studies of Inhibited Counterflow Flames written by Leonard F. Truett and published by . This book was released on 2001 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Studies of Laminar Counterflow Flames with Water Mist written by Riheng Zheng and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies in Structures of Laminar Hydrocarbon Flames written by Mary N. Bui-Pham and published by . This book was released on 1992 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure and Extinction of Counterflow Flames written by Ishwar Kanwar Puri and published by . This book was released on 1987 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical and Experimental Studies of Ethanol Flames and Autoignition Theory for Higher Alkanes written by Priyank Saxena and published by . This book was released on 2007 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research includes numerical, experimental and analytical studies. The first part of the dissertation consists of numerical and experimental studies of ethanol flames. Although ethanol has gained popularity as a possible low-pollution source of renewable energy, significant uncertainties remain in its combustion chemistry.
Download or read book The Frequency Response of Counterflow Diffusin Flames written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Most practical combustion processes rely on turbulent diffusion flames due to their higher heat release rates when compared to laminar diffusion flames. The higher heat release rates occur because of the increased mixing that results from the flame's interaction with the turbulent flow field. Unfortunately, the turbulent combustion process is very complex; therefore, simplified models have been constructed. Flamelet Theory is a method that characterizes turbulent diffusion flames as a collection of strained, laminar, one-dimensional flamelets. One caveat of this model is the flamelets are assumed to respond quasi-steadily to the applied flow field. The focus of my research has been to elucidate the influence of a time varying flow field on the combustion process. To test the response, the reaction zone of a propane-air counter-flow diffusion flame was subjected to time varying flow fields using speakers. The results of the experiments illustrate a reaction zone that responds quasi-steadily at forcing frequencies up to 50 Hz. Above this threshold, significant departures occur from steady flame behavior. At elevated frequencies, conditions were found where the reaction zone temperature was found to be in phase with the strain rate, signaling a significant deviation from the quasi-steady state assumption. In diffusion flames, the limiting step for the transport of reactants to the flame front is a diffusion process. The time associated with the increasing phase difference is likely a result of the time necessary for reactants to travel through the diffusion layer. As the forcing frequency is increased, the time rate of change of reactants delivered to the edge of the diffusive zone increases; however, a finite amount of time is still necessary for the reactants to diffuse to the flame front. As the forcing frequency increases, this diffusion time becomes larger relative to the cycle time of the oscillation, which in turn shows up as an increasing phase difference. Anot.
Download or read book Two dimensional Stability of Laminar Flames written by H. S. Mukunda and published by . This book was released on 1992 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
